Hi guys I'm new here, not new to Kawi's though
Just wondering if anyone could offer any input to my scenario..
I've got a mid 90's KLX250 as a field bike and as far as I'm aware it's the exact same bike just older and looks more outdated..
Anyway here is my situation:
I bought the bike and it ran fine up until about 1/2-3/4 revs and then it started to backfire and basically run like crap..

Checked the sparkplug and it was black so I've bought a replacement
Checked the air box and it doesn't have a lid on
Air filter is standard
Exhaust is standard
Elevation is about 0-1000 feet I think
Pilot jet is 35 (Standard)
Main jet is 135 (definatley not standard, infact I think it came off a mikuni carb )
Needle is standard
Mixture screw was about 2.5 turns out
And the slide hasn't been drilled with the looks of it,

Just wondering if anyone else is in the same sort of scenario as me and can tell me there setup..? Tried to check the jetting PDF file and there only seems to be about 3 people who have run it with the air box lid off
All three had non standard exhausts,
One of them didn't have the rest of the details filled in so wasn't really helpful
And another is about 5000 feet higher then I am lol

Any ball park figures to start at? I've replaced the 135 Mikuni jet to a 125 Keihin jet and I have a 130 keihin jet spare aswell
I am yet to put the carb back on the bike as I'm waiting for my drill bits to arrive so I can drill the carb slide and put it all back together as one

Just thought I would ask if anyone else has a similar setup before I put it all back together and realise I've made the problem worse..

So ideas/suggestions please?

 

Run some carb cleaner through it, the fuel maybe gunged up. Actually, if the fuel you got with it is still in it, drain it out and burn it in a bucket.

 

Sounds like it's way too rich at larger throttle openings. That main jet is most likely the problem.

There are a couple of other things to check, though. Check to see that the diaphragm is seated properly and not torn. Secondly, make sure the needle jet is still in the carb. They sometimes have a way of drifting off somewhere.

I'd suggest doing only one thing at a time. Try the smaller main jet first. Since the slide is so easy to get out, wait until you have the other problem fixed before making modifications to it. That way you shouldn't have to deal with compound issues.

Good luck.

Ron

 

Yeah, it is hard to tell with slider carbs, but it is either way too rich or way to lean.

From your symptoms it almost sounds like it is lean but the main jet is huge? I would simply just try to put an airbox lid back on it, I am betting that would make a huge difference.

Then maybe try a smaller main, otherwise the setup seems fine to me.